Anyone who only likes the original trilogy and hates the prequels is missing out on half of Star Wars. Sure they're not amazing, but it's still Star Wars whether you like it or not.
My favorites are Episodes V and III. Attack of the Clones can go jump off a cliff, and the Ewoks make ROTJ unbearable.
I group 3, 5, and 6 together since they're my favorites (though I tend to lean more towards 5). The only one I have a real problem with is Attack of the Clones; I just do not like that one.
I love all the movies, but personally Phantom Menace is my favorite. Of course it has the most annoying Star Wars character ever created, and the movie just wasn't well done, but it sets off everything that we know from the originals and helps have a better understanding of how things were prior to the Jedi massacre. You can all be close minded and hate it if you like, but it was still an intricate part of the series.
Also, Natalie Portman > Carrie Fisher all day
I would vote for all 3 original trilogy movies. The prequels don't exist to me. Redlettermedia on youtube explains quite well while I dislike them so much and why they are so nonsensical and ruin starwars.